Based On The Synthesis, Structure And Properties Of Two Flexible Carboxylic Acid Rare Earth Organic Skeletons

In this paper,two series of fourteen lanthanide coordination polymer have been obtained by the self assembly of two flixble carboxylate ligands（H₄BCBAIP=5-（bis（4-carboxybenzyl）amino）-isophthalicacidandH₃DCBBA=4-（3,5-dicarboxylatobenzyloxy）benzoic acid）with lanthanide ions.The crystal structures and luminescence properties of complexws were reaserched and the results are listed as following:1.A series of new isostructural lanthanide metal-organic frameworks（Ln-MOFs）,[Ln₂（DCBBA）₂（DMAC）₂]·nH₂O[Ln=La（1）,Pr（2）,Nd（3）,Sm（4）,Eu（5）,Gd（6）,Tb（7）and Tm（8）;H₄L=5-（bis（4-carboxybenzyl）amino）-isophthalic acid,DMAC=N,N′-dimethylacetamide],have been isolated.Single-crystal X-ray diffraction analysis reveals that all complexes exhibit a rare（4,8）-connected alb-4,8-P topology with binuclear[Eu₂（COO）₈]_n secondary building units as 8-connected nodes and H₄L ligands as 4-connected nodes.Two mixed-lanthanide analogues of single-lanthanide MOFs were design and prepared[Ln=La_0.93Eu_0.02Tb_0.05（9）and Tm_0.47Eu_0.18Tb_0.35（10）]by way of careful regulation of the relative concentration of lanthanide ions which are able to emit pure white light.Luminescent sensing of complexes 3 and 5 has been investigated.Strikingly,complex 5 exhibits an excellent luminescent sensing to TNP with a high K_sv value of 3.58×10⁴ M^-11 and low detection limit of 4.66×10^-44 mM.Complex 3 reveals high selectivity and sensitivity toward benzaldehyde(K_svv of 4.9×10⁴ M^-1;detection limit of 3.4×10^-44 mM).It represents the first example of NIR luminescent MOF for sensing of benzaldehyde.2.A series of isomorphic lanthanide metal-organic frameworks（Ln-MOFs）,namely[La（DCBBA）（DMF）₂]_n·0.5DMF[Ln=La（11）,Eu（12）and Tb（13）]have been designed and synthesized by the solvothermal reactions of H₃DCBBA and La（NO₃）₃·6H₂O.Single-crystal X-ray diffraction analysis reveals that the complexes1-3 exhibit a（3,6）-connected open framework structure.The isostructural mixed La/Eu/Tb-dcbba（4）was obtained via the in-suit doping of different Ln³⁺ions into the host framework,which is able to emit pure orange,white and blue light when excited at300,305 and 350 nm,respectively.Subsequently,a novel and multifunctional sensing process was designed based on the excitation wavelength sensitive color tunable luminescent sample 4,which can detect HS^–ions,THF（tetrahydrofuran）and Ag⁺ions via different luminescence color change mechanism.The remarkable color change,excellent selectivity and high sensitivity further indicate the promise of this type of multifunctional luminescent materials for the sensing of anion,cation and organic small molecule.